In microcontroller-based applications including internal memory (e.g. RAM) and peripheral interfaces, it is often required to modify the data stored in internal memories and registers (e.g. registers for interfaces to peripherals) by an external device. Known solutions use internal resources, like the internal central processing unit (CPU) or direct memory access (DMA) to perform this data modification. This suspends the normal internal operation of the microcontroller until the external access is accomplished, thereby slowing normal operation.